The subject invention is directed to a temperature control system for vehicles and, more particularly, to a variable temperature control system for controlling the temperature of air supplied to a vehicle's passenger compartment.
In the typical vehicle heating and air conditioning system, temperature controlling is accomplished by controlling the setting of a vent damper or blend door located in the passenger air supply system duct work. Often a rotary knob located at the control panel is drivingly connected to the blend door through a mechanical cable or linkage arrangement. The loads required to operate the blend door have generally required relatively rigid control cables and linkages.
Various proposals to simplify or improve the drive connection between the operating knob and the blend door have been presented. However, problems with respect to high operating knob force requirements and the routing the drive connection between the knob and blend door have persisted. In addition, readjustment of control cable length after installation has also been a problem.
A further drawback to prior systems has been the difficulty of achieving a linear relationship between knob movement and output air temperature. Generally, this has only been achievable through the use of electronic systems or by a mechanical system of cams and rigid push-pull cables. The electronic systems are costly, and the systems incorporating rigid push-pull cables present difficult routing problems and substantially limit the use of the systems.